Such an imaging device is useful for supplying three dimensional data to other instruments. For example, such data is valuable in the science of robotics, where objects are required to be identified on the basis of their three dimensional shape, and to be manipulated accordingly. Such data is also useful in monitoring the accuracy of the shape of a series of articles intended to be identical with each other. A three dimensional imaging device of this type is inexpensive to manufacture, high speed in operation, compact, and robust, and hence especially well adapted for use in robotics, e.g. for mounting on the end of a robot arm, although the utility of the present invention is by no means limited to robotics.